Exception "System.NullReferenceException: Unable to load module."

[EMaderbacher]

I get very often this exception:

System.NullReferenceException: Unable to load module.
   at BlazorStrap.Service.BlazorStrapInterop.PreloadModuleAsync(Nullable`1 cancellationToken)
   at BlazorStrap.Shared.Components.BSCoreBase.OnAfterRenderAsync(Boolean firstRender)
   at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

What I've seen in webserver logs this happens when

• The webpage is opened
• The webpage is closed immediatelly, is refreshed or any other reason that the circuit has been closed
• The exception is always shown exactly 1 minute after the webpage was opened

The code throwing the exception is found here: https://github.com/EMaderbacher/BlazorStrap/blob/cb2654ed79fac96290dbfe6d78019864ffc2cb1a/src/BlazorStrap/Service/BlazorStrapInterop.cs#L325 In other places a null check is made and no exception is thrown, like here: https://github.com/EMaderbacher/BlazorStrap/blob/cb2654ed79fac96290dbfe6d78019864ffc2cb1a/src/BlazorStrap/Service/BlazorStrapInterop.cs#L337 Any chance that the exception isn't thrown and instead of that a null check is made?

The same exception is thrown here too: https://github.com/EMaderbacher/BlazorStrap/blob/cb2654ed79fac96290dbfe6d78019864ffc2cb1a/src/BlazorStrap/Service/BlazorStrapInterop.cs#L307 May a similar exception is thrown in other places too?

[jbomhold3]

Should be safe to just return null for the preloaded. On AnimateCarouselAsync returning false on null should just keep the slide from changing if I remember correctly. Though not sure why the preloading is getting called at all right now from a state the js runtime isn't ready.

On Wed, Sep 18, 2024 at 12:38 AM EMaderbacher @.***> wrote:

I get very often this exception:

System.NullReferenceException: Unable to load module. at BlazorStrap.Service.BlazorStrapInterop.PreloadModuleAsync(Nullable`1 cancellationToken) at BlazorStrap.Shared.Components.BSCoreBase.OnAfterRenderAsync(Boolean firstRender) at Microsoft.AspNetCore.Components.RenderTree.Renderer.GetErrorHandledTask(Task taskToHandle, ComponentState owningComponentState)

What I've seen in webserver logs this happens when

• The webpage is opened
• The webpage is closed immediatelly, is refreshed or any other reason that the circuit has been closed
• The exception is always shown exactly 1 minute after the webpage was opened

The code throwing the exception is found here: https://github.com/EMaderbacher/BlazorStrap/blob/cb2654ed79fac96290dbfe6d78019864ffc2cb1a/src/BlazorStrap/Service/BlazorStrapInterop.cs#L325 In other places a null check is made and no exception is thrown, like here: https://github.com/EMaderbacher/BlazorStrap/blob/cb2654ed79fac96290dbfe6d78019864ffc2cb1a/src/BlazorStrap/Service/BlazorStrapInterop.cs#L337 Any chance that the exception isn't thrown and instead of that a null check is made?

The same exception is thrown here too: https://github.com/EMaderbacher/BlazorStrap/blob/cb2654ed79fac96290dbfe6d78019864ffc2cb1a/src/BlazorStrap/Service/BlazorStrapInterop.cs#L307 May a similar exception is thrown in other places too?

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[jbomhold3]

I removed the thrown exceptions. The preloader doesn't care if it returns null and likely never should have. AnimateCarouselAsync will not just return true bypassing the animation.

[jbomhold3]

I also wrapped NextAsync and BackAsync in a try-catch. This is because when navigating the timer might have just triggered and the task is still working. Since the elements are gone the array was out of range.